The present disclosure relates to an optical film and a liquid crystal display device including the same.
Recently, as various portable devices such as a mobile phone, a Personal Digital Assistant (PDA), and a notebook computer are developed, a need for a thin, light, and small flat panel display device applicable thereto has increased. For developing such a flat panel display device, researches are actively conducted on a Liquid Crystal Display (LCD), a Plasma Display Panel (PDP), a Field Emission Display (FED), a Vacuum Fluorescent Display (VFD), and the like. Particularly, an LCD is in the spotlight because of the advantages of mass producibility, simple driving means, high-definition, and large-sized screen.
An LCD is a transmissive display device, which adjusts the intensity of light which transmits through a liquid crystal layer using an anisotropic refractive index of liquid crystal particles to display an image on a screen. Therefore, a backlight may be installed in an LCD as a source of light which transmits through the liquid crystal layer to display an image. Generally, a backlight is roughly classified into two kinds.
The first kind is a side-light-type backlight which is installed on a side of a liquid crystal panel to provide light, and the second kind is a direct-light-type backlight which directly provides light under a liquid crystal panel.
The side-light-type backlight installed on a side of a liquid crystal display may provide light to a liquid crystal layer through a reflection plate and a light guide plate. Therefore, an LCD adopting the side-light-type backlight may be designed to be thin, and is typically used in an electronic device such as a notebook computer which needs a thin display device.
However, since a lamp of the side-light-type backlight which emits light is located on a side of a liquid crystal panel, it is difficult to apply the side-light-type backlight to a large-sized liquid crystal panel. Moreover, since light is supplied via the light guide plate, it is difficult to obtain high brightness. Therefore, the side-light-type backlight may not be suitable for use in a liquid crystal panel for a recently spotlighted large screen LCD TV.
Since the direct-light-type backlight supplies light directly to a liquid crystal layer, the direct-light-type backlight is more applicable to a large-sized liquid crystal panel and high brightness may be obtained. Therefore, the direct-light-type backlight is typically used for manufacturing a liquid crystal panel for an LCD TV.
Meanwhile, characteristics of light generated from a light source are changed while the light passes through various optical films before the light is supplied to a liquid crystal panel. Theses optical films may diffuse, reflect, and shield the light to improve light efficiency and process efficiency.